Effect of ignition chemistry on turbulent premixed flames of n-heptane and toluene

Sang Hee Won, Christopher B. Reuter, Shinya Nakane, Yiguang Ju, Bret Windom

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Turbulent premixed flames of n-heptane/air and toluene/air mixtures have been experimentally investigated in a reactor-assisted turbulent SLot (RATS) burner at two burner temperatures, 450 K and 650 K, by measuring turbulent burning velocities (ST), flashback, and flame structures with planar laser-induced fluorescence (PLIF) imaging at various equivalence ratios (φ). Turbulent burning velocities have been found to be affected by the low-temperature-ignition for n-heptane/air mixture due to two-stage ignition process, whereas no LTI affected turbulent burning velocity is found in case of toluene/air mixture due to the absence of two-stage ignition process. The measured turbulent burning velocities of n-heptane and toluene at 450 K exhibits identical trend of u’/SL dependency, once they are normalized by the laminar burning velocities (SL), indicating appropriate representation of chemical effect by SL. In order to investigate the effect of Lewis number (Le), turbulent burning velocities and flame structure are measured by changing the equivalence ratio from 0.7 to 1.5 at 450 K. The results show that ST is insensitive to the change of Le at fuel lean, however strong dependency of ST on Lewis number is found at fuel rich conditions due to the increase of flame front wrinkling. Flame flashback conditions are measured in a function of mean jet velocity and equivalence ratio for n-heptane/air mixtures from lean (φ = 0.7) to rich (2.1) cases. The flashback measurements reveal completely different behaviors, depending on the burner temperature. At 450 K (chemically-frozen regime) the flashback is found to be controlled by the turbulent burning velocity, whereas at 650 K (Ignition-driven regime) the flashback is correlated well with the calculated hot-ignition delay times of n-heptane/air mixture. In ignition-driven regime, the measured ST/SL increases substantially as increasing the ignition Damkőhler number.

Original languageEnglish (US)
Title of host publication53rd AIAA Aerospace Sciences Meeting
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624103438
DOIs
StatePublished - Jan 1 2015
Event53rd AIAA Aerospace Sciences Meeting, 2015 - Kissimmee, United States
Duration: Jan 5 2015Jan 9 2015

Publication series

Name53rd AIAA Aerospace Sciences Meeting

Other

Other53rd AIAA Aerospace Sciences Meeting, 2015
CountryUnited States
CityKissimmee
Period1/5/151/9/15

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering

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  • Cite this

    Won, S. H., Reuter, C. B., Nakane, S., Ju, Y., & Windom, B. (2015). Effect of ignition chemistry on turbulent premixed flames of n-heptane and toluene. In 53rd AIAA Aerospace Sciences Meeting [AIAA 2015-0430] (53rd AIAA Aerospace Sciences Meeting). American Institute of Aeronautics and Astronautics Inc, AIAA. https://doi.org/10.2514/6.2015-0430